In the primary invention of this application, an optical-fiber inspection device which detects the distance to a reflection point within the DUT and the amount of reflected light by dividing into two a laser beam which is possible to be frequency-swept, making one of the divided light be

A first invention of the present application is an optical spectrum analyzer comprising a spectrometer apparatus an arithmetic unit for calculating the center wavelength from output signals from photo detector devices of a device array included in the spectrometer apparatus and from

In the primary invention of this application, an optical-fiber inspection device which detects the distance to a reflection point within the DUT and the amount of reflected light by dividing into two a laser beam which is possible to be frequency-swept, making one of the divided light be